How does a pacemaker keep a heart beating regularly?

A pacemaker is a small implanted device with a battery and one or more leads placed near the heart. It senses the heart’s electrical activity and delivers timed pulses when the heartbeat falls below a programmed rate or misses a beat. This helps patients with bradycardia and certain conduction disorders maintain a safe rhythm. The first fully implantable pacemaker was developed in 1958 by Swedish engineer Rune Elmqvist and surgeon Åke Senning. Today's devices are much smaller, longer-lasting, and can often be checked remotely by doctors.